Detection method, detection device, and lidar

Abstract

A detection method includes obtaining first count data and second count data during rotation of an encoder disc mounted at and configured to rotate together with a rotation object and determining a rotation parameter of the rotation object according to the first count data and the second count data. The encoder disc includes N detection target portions arranged along a circumferential direction of the encoder disc. The N detection target portions include N−K first detection target portions and K second detection target portions. Along the circumferential direction of the encoder disc, a width of one of the N−K first detection target portions is different from a width of one of the K second detection target portions. The first count data is obtained when one detection target portion of the N detection target portions is detected. The second count data is recorded between two neighboring detection target portions.

What is claimed is: 
     
         1 . A detection method comprising:
 obtaining first count data and second count data during rotation of an encoder disc mounted at and configured to rotate together with a rotation object; and   determining a rotation parameter of the rotation object according to the first count data and the second count data, the rotation parameter including a rotation angle and a rotation speed;   wherein:
 the encoder disc includes N detection target portions arranged along a circumferential direction of the encoder disc, N being an integer greater than two; 
 the N detection target portions include N−K first detection target portions and K second detection target portions, K being an integer greater than or equal to 1 and smaller than N; 
 along the circumferential direction of the encoder disc, a width of one of the N−K first detection target portions is different from a width of one of the K second detection target portions; 
 the first count data is obtained when one detection target portion of the N detection target portions is detected; and 
 the second count data is recorded between two neighboring detection target portions of the N detection target portions. 
   
     
     
         2 . The method of  claim 1 , wherein:
 the first count data includes a count value; and   obtaining the first count data includes:
 in response to detecting a zero position of the encoder disc, clearing the count value; and 
 in response to detecting the one detection target portion, obtaining the count value. 
   
     
     
         3 . The method of  claim 2 , wherein the zero position of the encoder disc corresponds to a position of one of the K second detection target portions. 
     
     
         4 . The method of  claim 1 , wherein:
 the second count data includes a count value; and   obtaining the second count data includes:
 in response to detecting one of the N−K first detection target portions or one of the K second detection target portions, clearing the count value; and 
 in response to receiving a trigger signal, obtaining the count value. 
   
     
     
         5 . The method of  claim 4 , wherein the trigger signal includes a signal triggered when the rotation object emits light and/or receives light. 
     
     
         6 . The method of  claim 1 , wherein:
 the first count data includes a first count value and the second count data includes a second count value;   determining the rotation parameter of the rotation object according to the first count data and the second count data includes:
 determining a rotation angle in a current rotation round of the encoder disc by using the first count value obtained in a last rotation round of the encoder disc and the second count value obtained in the current rotation round of the encoder disc; and 
   the rotation angle in the current rotation round of the encoder disc is a rotation angle in the current rotation round of the rotation object.   
     
     
         7 . The method of  claim 6 , wherein:
 determining the rotation angle in the current rotation round of the encoder disc by using the first count value obtained in the last rotation round of the encoder disc and the second count value obtained in the current rotation round of the encoder disc includes:
 in response to receiving a trigger signal, determining the rotation angle in the current rotation round of the encoder disc by using the first count value obtained in the last rotation round of the encoder disc, the second count value obtained in the current rotation round of the encoder disc, and an accumulation value of the first count value obtained in the last rotation round of the encoder disc, of a last detection target portion in a rotation direction of the encoder disc; 
   
     
     
         8 . The method of  claim 1 , wherein:
 the first count data includes a first count value and a first count frequency;   the second count data includes a second count value and a second count frequency;   determining the rotation parameter of the rotation object according to the first count data and the second count data includes:
 determining a rotation speed of the encoder disc according to the first count frequency and the first count value; and 
   the rotation speed of the encoder disc is the rotation speed of the rotation object.   
     
     
         9 . The method of  claim 8 , wherein:
 determining the rotation speed of the encoder disc according to the first count frequency and the first count value includes:
 determining a time length needed for the encoder disc to rotate for a round according to the first count frequency and the first count value to determine the rotation speed of the encoder disc. 
   
     
     
         10 . The method of  claim 1 , wherein:
 along the circumferential direction of the encoder disc, the encoder disc is divided into N detection areas;   each of the N detection areas includes one of the detection target portions and an encoder disc portion; and   the detection target portions and the encoder disc portions are arranged alternately.   
     
     
         11 . The method of  claim 10 , wherein:
 the N encoder disc portions include N−K first encoder disc portions and K second encoder disc portions; and   along the circumferential direction of the encoder disc:
 the width of the one of the first detection target portions is smaller than the width of the one of the second detection target portions; and 
 a width of one of the N−K first encoder disc portions is greater than a width of one of the K second encoder disc portions. 
   
     
     
         12 . The method of  claim 11 , wherein, along the circumferential direction of the encoder disc:
 the width of the one of the first detection target portions is equal to the width of the one of the second encoder disc portions;   the width of the one of the second detection target portions is equal to the width of the one of the first encoder disc portions; and   the width of the one of the second detection target portions is three times the width of the one of the first detection target portions.   
     
     
         13 . The method of  claim 1 , wherein one of the detection target portions includes a through-hole, a magnetic member, a light transmission member, or a light reflection member. 
     
     
         14 . A detection device comprising:
 an encoder disc configured to be mounted at and rotate together with a rotation object, wherein:
 the encoder disc includes N detection target portions arranged along a circumferential direction of the encoder disc, N being an integer greater than 2; 
 the N detection target portions include N−K first detection target portions and K second detection target portions, K being an integer greater than or equal to 1 and smaller than N; 
 along the circumferential direction of the encoder disc, a width of one of the N−K first detection target portions is different from a width of one of the K second detection target portions; 
   a detection member configured to detect the first detection target portions and the second detection target portions; and   a processor configured to in rotation of the encoder disc:
 obtain first count data when one detection target portion of the N detection target portions is detected and second count data between two neighboring detection target portions of the N detection target portions; and 
 determine a rotation parameter of the rotation object according to the first count data and the second count data, the rotation parameter including a rotation angle and a rotation speed. 
   
     
     
         15 . The device of  claim 14 , wherein:
 the first count data includes a count value; and   the processor is further configured to:
 in response to detecting a zero position of the encoder disc, clear the count value; and 
 in response to detecting the one detection target portion, obtain the count value. 
   
     
     
         16 . The device of  claim 14 , wherein:
 the second count data includes a count value; and   the processor is further configured to:
 in response to detecting one of the N−K first detection target portions or one of the K second detection target portions, clearing the count value; and 
 in response to receiving a trigger signal, obtaining the count value. 
   
     
     
         17 . The device of  claim 14 , wherein:
 the first count data includes a first count value and a first count frequency;   the second count data includes a second count value and a second count frequency;   the processor is further configured to:
 determine a rotation speed of the encoder disc according to the first count frequency and the first count value; and 
   the rotation speed of the encoder disc is the rotation speed of the rotation object.   
     
     
         18 . The device of  claim 14 , wherein:
 along the circumferential direction of the encoder disc, the encoder disc is divided into N detection areas;   each of the N detection areas includes one of the detection target portions and an encoder disc portion; and   the detection target portions and the encoder disc portions are arranged alternately.   
     
     
         19 . A LIDAR comprising:
 an optical element;   a driver for driving the optical element to rotate; and   a detection device configured to detect a rotation parameter of the optical element and including:
 an encoder disc configured to be mounted at and rotate together with the optical element, wherein:
 the encoder disc includes N detection target portions arranged along a circumferential direction of the encoder disc, N being an integer greater than 2; 
 the N detection target portions includes N−K first detection target portions and K second detection target portions, K being an integer greater than or equal to 1 and smaller than N; 
 along the circumferential direction of the encoder disc, a width of one of the N−K first detection target portions is different from a width of one of the K second detection target portions; 
 
 a detection member configured to detect the first detection target portions and the second detection target portions; and 
 a processor configured to in rotation of the encoder disc:
 obtain first count data when one detection target portion of the N detection target portions is detected and second count data between two neighboring detection target portions of the N detection target portions; and 
 determine the rotation parameter of the optical element according to the first count data and the second count data, the rotation parameter including a rotation angle and a rotation speed. 
 
   
     
     
         20 . The LIDAR of  claim 19 , wherein the optical element includes a prism or a lens. 
     
     
         21 . The LIDAR of  claim 20 , wherein:
 the prism has different thicknesses along a radial direction; and   the one of the K second detection target portions is aligned to a position where the prism has a minimal or maximal thickness.   
     
     
         22 . The LIDAR of  claim 19 , wherein:
 the optical element is arranged in a lens barrel;   the lens barrel includes a snap piece;   the encoder disc includes a snap slot; and   the snap piece is at least partially snapped in the snap slot to mount the encoder disc at the lens barrel.